Inflammation and adaptive immune responses play opposing roles in regulating tumor development, progression, and metastasis. Interleukin-6 (IL-6) is a pleiotropic cytokine with both pro- and anti-inflammatory properties and also acts directly on cancer cells to promote their survival and proliferation. Serum IL-6 levels are elevated and negatively associated with survival of cancer patients, which is generally attributed to the direct effects of IL-6 on cancer cells. There is a need in the art to further elucidate IL-6 modulation of the host immune response in cancer patients. The present disclosure addresses these and other needs in the art.